> * Andrea Righi <arighi@develer.com> [2010-03-15 00:26:38]:> > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>> > > > Now, file-mapped is maintaiend. But more generic update function> > will be needed for dirty page accounting.> > > > For accountig page status, we have to guarantee lock_page_cgroup()> > will be never called under tree_lock held.> > To guarantee that, we use trylock at updating status.> > By this, we do fuzzy accounting, but in almost all case, it's correct.> >> > I don't like this at all, but in almost all cases is not acceptable> for statistics, since decisions will be made on them and having them> incorrect is really bad. Could we do a form of deferred statistics and> fix this.>

plz show your implementation which has no performance regresssion.For me, I don't neee file_mapped accounting, at all. If we can remove that,we can add simple migration lock.file_mapped is a feattue you added. please improve it.